Antiseptic

Antiseptics (from Greekαντί - anti, '"against" + σηπτικός - septikos, "putrefactive") are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. Antiseptics are generally distinguished from antibiotics by the latter's ability to be transported through the lymphatic system to destroy bacteria within the body, and from disinfectants, which destroy microorganisms found on non-living objects. Some antiseptics are true germicides, capable of destroying microbes (bacteriocidal), whilst others are bacteriostatic and only prevent or inhibit their growth. Antibacterials are antiseptics that have the proven ability to act against bacteria. Microbicides which kill virus particles are called viricides or antivirals.

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Usage in surgery

The widespread introduction of antiseptic surgical methods followed the publishing of the paper Antiseptic Principle of the Practice of Surgery in 1867 by Joseph Lister, inspired by Louis Pasteur's germ theory of putrefaction. In this paper he advocated the use of carbolic acid (phenol) as a method of ensuring that any germs present were killed. Some of this work was anticipated by:

Dr. George H Tichenor who experimented with the use of alcohol on wounds ca. 1861–1863, and subsequently marketed a product for this purpose known as "Dr. Tichenor's Patent Medicine" after the American Civil War.

Ignaz Semmelweis who published his work The Cause, Concept and Prophylaxis of Childbed Fever in 1861, summarizing experiments and observations since 1847.[1]

Florence Nightingale, who contributed substantially to the report on the Royal Commission on the Health of the Army (1856–1857), based on her earlier work.

and even the ancient Greek physicians Galen (ca. 130–200 AD) and Hippocrates (ca. 400 BC). There is even a Sumerian clay tablet dating from 2150 BC advocating the use of similar techniques.[2]

But every antiseptic, however good, is more or less toxic and irritating to a wounded surface. Hence it is that the antiseptic method has been replaced in the surgery of today by the aseptic method, which relies on keeping free from the invasion of bacteria rather than destroying them when present.

How it works

For the growth of bacteria there must be a food supply, moisture, in most cases oxygen, and a certain minimum temperature (see bacteriology). These conditions have been studied and applied in food preservation and the ancient practice of embalming the dead, which is the earliest known systematic use of antiseptics.

In early inquiries, there was much emphasis on the prevention of putrefaction, and procedures were carried out to find how much of an agent must be added to a given solution in order to prevent development of undesirable bacteria. However, for various reasons, this method was inaccurate, and today an antiseptic is judged by its effect on pure cultures of defined pathogenic celicular single helix microbes and their vegetative and spore forms. The standardization of antiseptics has been implemented in many instances, and a water solution of phenol of a certain fixed strength is now used as the standard to which other antiseptics are compared.

Some common antiseptics

Most commonly used are ethanol (60–90%), 1-propanol (60–70%) and 2-propanol/isopropanol (70–80%) or mixtures of these alcohols. They are commonly referred to as "surgical alcohol". Used to disinfect the skin before injections are given, often along with iodine (tincture of iodine) or some cationic surfactants (benzalkonium chloride 0.05–0.5%, chlorhexidine 0.2–4.0% or octenidine dihydrochloride 0.1–2.0%).

Quaternary ammonium compounds

Also known as Quats or QAC's, include the chemicals benzalkonium chloride (BAC), cetyl trimethylammonium bromide (CTMB), cetylpyridinium chloride (Cetrim, CPC) and benzethonium chloride (BZT). Benzalkonium chloride is used in some pre-operative skin disinfectants (conc. 0.05–0.5%) and antiseptic towels. The antimicrobial activity of Quats is inactivated by anionic surfactants, such as soaps. Related disinfectants include chlorhexidine and octenidine.

Used in suppositories to treat yeast infections of the vagina, in eyewashes, and as an antiviral to shorten the duration of cold sore attacks. Put into creams for burns. Also common in trace amounts in eye contact solution.

Brilliant Green

A triarylmethane dye still widely used as 1% ethanol solution in Eastern Europe and ex-USSR countries for treatment of small wounds and abscesses. Efficient against gram-positive bacteria.

Chlorhexidine Gluconate

A biguanidine derivative, used in concentrations of 0.5–4.0% alone or in lower concentrations in combination with other compounds, such as alcohols. Used as a skin antiseptic and to treat inflammation of the gums (gingivitis). The microbicidal action is somewhat slow, but remanent. It is a cationic surfactant, similar to Quats.

Used as a 6% (20 Vols) solution to clean and deodorize wounds and ulcers. More common 3% solutions of hydrogen peroxide have been used in household first aid for scrapes, etc. However, even this less potent form is no longer recommended for typical wound care as the strong oxidization causes scar formation and increases healing time. Gentle washing with mild soap and water or rinsing a scrape with sterile saline is a better practice.

Usually used in an alcoholic solution (called tincture of iodine) or as Lugol's iodine solution as a pre- and post-operative antiseptic. No longer recommended to disinfect minor wounds because it induces scar tissue formation and increases healing time. Gentle washing with mild soap and water or rinsing a scrape with sterile saline is a comparatively better practice. Novel iodine antiseptics containing povidone-iodine (an iodophor, complex of povidone, a water-soluble polymer, with triiodide anions I3-, containing about 10% of active iodine) are far better tolerated, don't negatively affect wound healing, and leave a deposit of active iodine, thereby creating the so-called "remnant," or persistent, effect. The great advantage of iodine antiseptics is its wide scope of antimicrobial activity, killing all principal pathogens and, given enough time, even spores, which are considered to be the most difficult form of microorganisms to be inactivated by disinfectants and antiseptics.

Mercurochrome

Not recognized as safe and effective by the U.S. Food and Drug Administration (FDA) due to concerns about its mercury content. Other obsolete organomercury antiseptics include bis-(phenylmercuric) monohydrogenborate (Famosept).

Manuka Honey

Recognized by the U.S. Food and Drug Administration (FDA) as a medical device for use in wounds and burns. Active +15 is equal to a 15% solution of phenol.

Octenidine dihydrochloride

A cationic surfactant and bis-(dihydropyridinyl)-decane derivative, used in concentrations of 0.1–2.0%. It is similar in its action to the Quats, but is of somewhat broader spectrum of activity. Octenidine is currently increasingly used in continental Europe as a QAC's and chlorhexidine (with respect to its slow action and concerns about the carcinogenic impurity 4-chloroaniline) substitute in water- or alcohol-based skin, mucosa and wound antiseptic. In aqueous formulations, it is often potentiated with addition of 2-phenoxyethanol.

Phenol is germicidal in strong solution, inhibitory in weaker ones. Used as a "scrub" for pre-operative hand cleansing. Used in the form of a powder as an antiseptic baby powder, where it is dusted onto the navel as it heals. Also used in mouthwashes and throat lozenges, where it has a painkilling effect as well as an antiseptic one. Example: TCP. Other phenolic antiseptics include historically important, but today rarely used (sometimes in dental surgery) thymol, today obsolete hexachlorophene, still used triclosan and sodium 3,5-dibromo-4-hydroxybenzenesulfonate (Dibromol).

are the main type of compound found in essential oils, and some have reasonably strong antibacterial, antifungal and antiviral properties. For example Terpinen-4-ol is found in Tea tree oil.

Evolved resistance

Stuart B. Levy, in a presentation to the 2000 Emerging Infectious Diseases Conference, expressed concern that the over use of antiseptic and antibacterial agents might lead to an increase in dangerous, resistant strains of bacteria.[5] The theory states that this could cause bacteria to evolve to the point where they are no longer harmed by antiseptics.

Different antiseptics differ in how they cause bacteria to evolve, which leads to genetic defenses against particular compounds. It can also be dose dependent; resistance can occur at low doses but not at high; and resistance to one compound can sometimes increase resistance to others.